Mitochondrial Myopathies

They include several diseases of mitochondria, the organs of the cells responsible for energy production. By this term we refer to the following muscle abnormalities:

  • Kearns Syndrome – Sayre (KSS)
  • Leigh’s Syndrome
  • Mitochondrial Depletion Syndrome (MDS)
  • Mitochondrial encephalomyopathy
  • Lactic acidosis with stroke-type episodes (MELAS) (see also Congenital Myopathies)
  • Myoclonic epilepsy (MERRG)(Congenital Myopathies)
  • Mitochondrial neurotrophic encephalopathy syndrome (MNGIE)
  • Neuropathy, ataxia and retinitis pigmentosa (NARP)
  • Pearson’s Syndrome
  • Chronic evolutionary external ophthalmoplegia (CPEO)

Many genes are involved in either mitochondrial or nuclear genetic material and mutations may result in this condition, which are either inherited either by the mother or by both parents respectively, or they may be sporadic.

Some of the symptoms that may occur are:

Myopathy: muscle fatigue and weakness, lack of endurance leading to rhabdomyolysis and cramps, opthalmoplegia, ptosis, skeletal muscle abnormalities,  difficulty in swallowing.

Encephalopathy: ptoic atrophy, retinopathy, kophosis, migraines, ataxia and seizures.

Breathing problems

Cardiac manifeastations: cardiomyopathy, arrythmias.

Other: gastrointestinal disorders, learning difficulties, renal dysfuction, diabetes.

Diagnosis

  • Clinical examination by specialist physicians and neurologists,
  • Muscle biopsy,
  • Genetic test,
  • CT and MRI,
  • ECG,
  • Electrocardiogram and muscle ultrasound,
  • Blood tests for liver and kidney monitor.

Management

There is no cure, but treatment of each symptom. Indicatively interventions include use of hearing aids and glasses, appropriate medication (eg. for treating crises and pain), use of ancillary means of movement (eg use of cane, wheelchair), occupational and speech therapy, temporary or permanent respiratory support, dietary supplements (eg creatine, L-carnitine, coenzyme Q10).

Follow the Standards of Care:

Patient care standards for primary mitochondrial disease A consensus statement from the Mitochondrial Medicine Society

To monitor clinical trials on the disease, visit: https://clinicaltrials.gov/ct2/home

Useful links:

  1. https://www.orpha.net/consor/cgi-bin/Disease_Search_Simple.php?lng=EN&diseaseGroup=mitochondrial+myopathy
  2. https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Mitochondrial-Myopathy-Fact-Sheet#What%20are%20mitochondrial%20myopathies?

 

References

  • A. W. El-Hattab, F. Scaglia, Mitochondrial DNA Depletion Syndromes: Review and Updates of Genetic Basis, Manifestations and Therapeutic Options, Neurotherapeutics, 2013, 10, p. 186–198.
  • Santorelli F.M., Tessa A., Neuropathy, Ataxia and retinitis pigmentosa (NARP) syndrome, Orphanet Encyclopedia, 2004.
  • Muscular Dystrophy Association, About Neuromuscular Diseases, June 08, 2017, https://www.mda.org/disease/

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